The Tungurahua volcano spews a large cloud of ash towards the nearby town of Bilbao, Ecuador, in the early hours of August 21, 2012.

The volcano spews large clouds of gas and ash near Banos, about 110 miles south of Quito, on August 20, 2012.

The volcano spews ash towards the nearby town of Banos on August 21, 2012.

A view of the volcano on August 20, 2012.

Ecuador's Tungurahua volcano spews large clouds of gas and ash near Banos, about 110 miles south of Quito Aug. 19. The authorities are encouraging residents living near the volcano to evacuate due to increased activity of the volcano. The Tungurahua volcano has been in an active state since October 1999.

A cow covered with ashes is seen in the skirts of the Tungurahua volcano after it began spewing large clouds of gas and ash.

A plume of smoke comes out the Tungurahua volcano after it erupted as seen from Cotalo, Ecuador, Wednesday, Nov. 30, 2011. Ecuador's Geophysical Institute said the volcano's increased activity that began Sunday, is billowing columns of ash, sending superheated clouds of gas down the slopes and cascading hot rocks from the summit.

A view of the Tungurahua volcano as it erupts as seen from Cotalo, Ecuador, Wednesday, Nov. 30, 2011. Ecuador's Geophysical Institute said the volcano's increased activity that began Sunday, is billowing columns of ash, sending superheated clouds of gas down the slopes and cascading hot rocks from the summit.